Abstract: Process for stripping, by electroless chemical method, a surface-protection layer (3) with a high chromium content from the main body (2) of a component composed of a nickel-based or cobalt-based superalloy by immersion in a chloride solution (1) which does not release oxygen, which contains iron (III) and copper (II) and which contains still further additives, but no components of any kind which form chromium oxide. Temperature of the bath 50.degree. to 70.degree. C. Duration of residence of the component in the bath 10 to 150 h.Typical bath composition:200-400 gl: FeCl.sub.3 . 6H.sub.2 O0.5-5 gl: CuCl.sub.2 . 2H.sub.2 O10-20 m/l: Glycerol120-200 m/l: Concentrated HClRemainder: H.sub.

Abstract: Process for electrolytically detaching a high chromium and nickel and/or cobalt containing protective coating (7) from a base metal (4) that is made of a nickel-based or cobalt-based superalloy by means of activation in NaOH and HCl and subsequent submersion as the anode into an electrolyte (2), which contains oxidizing components that release oxygen.In the electrolytic process the chromium-depleted and nickel-enriched diffusion zone (9) of the protective coating (7) is preferably attacked and detached; said zone developing electro-negatively with respect to the surrounding regions.

Abstract: A method of electrolytically polishing Fe-, Co-, and Ni alloys, particularly nickel superalloys, wherein at least one fluorine compound is mixed into the electrolyte, which electrolyte is based on a strong acid and is further comprised of at least one weakly polar organic compound and a fluorinated surfactant. The preferred fluorine compound is HBF.sub.4, added the amount of 5 to 40 vol. %. Other fluorine compounds which perform well are ammonium bifluoride, HF, and sodium fluosilicate.

Abstract: A method for purifying aqueous residues from exhausted metallizing baths, which contain at least one amino compound as a complex-forming agent, which comprises anodically treating the aqueous residue containing heavy metal ions and complex-forming agent at a voltage, current density and time sufficient to eliminate the complexing ability of the amino compound, and removing the heavy metal ions from said aqueous residue.